Grammatical Framework

Grammatical Framework (GF) is a functional programming language specialised for linguistics.

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One of the key ideas in multilingual grammars is that an abstract syntax need not care about features like morphology, agreement, word order, and discontinuity. The abstract syntax is, to use linguistic terminology, purely about constituency: it tells what the constituents— that is, significant parts—of an expression are, without telling what they exactly look like or what their linear order is.

Tables vs. functions

The domain of a table must be a parameter type, ensuring the table represents a finite set of pairs.

Declarations

• fun and lin are abstract and concrete grammatical constructs. kinda like data constructors.

• cat and lincat are abstract and concrete types

• oper is for normal functions (called operations).

Pattern macros

GF has pattern macros, similar to Haskell's pattern synonyms.[cite:@ranta2004grammatical]

  vowel : pattern Str
    = #("a" | "e" | "i" | "o" | "u" | "y") ;
  vowelFinal : Str -> Str
    = \s -> case s of {
      xs + #vowel => "Ends in vowel" ;
      _ => "Ends in consonant"
    } ;

Pattern macros can be paramaterised, but unfortunately seem to be limited in that they cannot be used inline in case-expressions, thus preventing variable bindings and such.

  -- Example per Inari Listenmaa on the GF Discord.
  oper 
      foo : pattern Str = #("foo"|"FOO"|"Foo") ;
      bar : pattern Str = #("bar"|"BAR"|"Bar") ;

      commaSeparated : (x,y : pattern Str) -> pattern Str
        = \x,y -> #(x + "," + y) ;

      foobar : pattern Str = commaSeparated foo bar ;

  -- If not using function, need to include the #
  -- foobar : pattern Str = #(#foo + "," + #bar) ;

      test : Str -> Str = \s -> case s of {
        #foobar => s ++ "matched the pattern made of subpatterns!" ;
        _       => s ++ "did not match"
      } ;

References

• [cite:@ranta2004grammatical]